Non-magnetizable components of the pre-cited type are used, for instance, in highly sensitive magnetic fields or applications. Non-magnetizable rolling bearing components are also used, for example, in electromechanical appliances at locations where the magnetic flux must not be interrupted. Another reason for their use is their relatively high corrosion resistance.
It is known from the prior art to enhance the hardness of rolling bearing components by work hardening methods. A drawback of these methods is, however, that work hardening methods that lead to hardness values of more than 450 HV cause the formation of deformation martensite in the microstructure of the rolling bearing component. This renders the component magnetizable, so that it can no longer be used in applications in which non-magnetizable components with higher load capacity are required. Due to the only low hardness values achievable by work hardening, rolling bearing components made by these methods possess a load bearing capacity of approximately only 25% of that of comparable conventional rolling bearing components.
DE 35 37 658 C2 discloses a method of making a hardened, non-magnetizable rolling bearing component out of an austenitic material. In this method, the surface-proximate layer of the material of the rolling bearing component is carburized at elevated temperature in an oxygen-rich atmosphere and subsequently cooled. This prior art document also describes a rolling bearing component made by the described method. The rolling bearing component can be made of one of the following austenitic materials: X 5 CrNi 18 9, X 12 CrNiS 18 8, X 12 CrNi 17 7 or X 10 CrNiTi 18 9. The method enables surface hardness values of about 550 to 600 HV.
The quality of hardened components depends to a great extent on the depth of their hardness. It is true that with the method known from the prior art document DE 35 37 658 C2 good surface hardness values can be achieved but, already at a slight depth, only comparatively low hardness values are determined. In addition, for the carburization treatment, the prior art method requires relatively long sojourn times in the furnace. The small depths of precipitation hardness obtained in prior art materials limit the use of such materials considerably.